The most useful feature I would recommend you try to include is USB 3.0. The big advantage over eSATA is no external power supply required for external 2.5" or SSD drives (yes I know laptops may have eSATA-USB combo ports to solve that, but peripherals to suit are very uncommon).
I'd rank an external backup as a higher priority than an internal one, i.e. something that isn't normally in the same place. I've read (but haven't confirmed) that the
Samsung S2 USB 3.0 series are 7200rpm drives, which would make them the pick of the current crop.
It's really hard to go past a Samsung F4 2TB drive - buy 2 before Seagate takes them off the market. Although 5400rpm, their real-world performance is still very good compared to old 7200rpm drives. I personally favor an SSD boot drive, but it adds to the cost considerably. You could partition the drive with a view to migrating the boot partition to an SSD at a later date: 60GB for no games, 120GB for a gamer.
For a low budget, go for an AMD X2 265 (3.3GHz). Fully-featured motherboards to suit are also cheaper than Intel equivalents.
Next step up for me would be an Intel i3 2100 (3.1GHz). You would couple that with an
H67 chipset motherboard (H61 doesn't have SATA 3, although you may not care). I don't think people here can see the point in Z68 at this stage; it relies on you ponying up a further $100 or so to Intel for a 20MB SSD cache - for that you can buy a real SSD and a less expensive motherboard.
An Intel i5 2400 swaps hyperthreading for twice as many cores (4), so it's a lot gruntier. You can double the integrated graphics performance with an i5 2500K, or would he be more likely to add a separate graphics card down the track? BTW, the K suffix ones are unlocked for overclocking ...
Performance of this Sandy Bridge stuff is so high, I don't know if it's worth going any further, but top of the range is an i7 2600k. It's identical to the 2500K except that hyperthreading has reappeared.
HTH.
